IPA: /ˈvɪʃiˌeɪtə/
KK: /ˈvɪʃiˌeɪtər/
A person or thing that damages or weakens something, making it less effective or pure.
The vitiator of the agreement caused many problems for both parties involved.
Vitiator → It is formed from "viti-" (from Latin "vitium", meaning fault or defect) and "-ator" (a suffix indicating an agent or doer). The word "vitiator" refers to one who causes a fault or defect, essentially a corrupter.
Think of someone who causes a 'fault' ('viti-') — that's why a vitiator is someone who corrupts or damages something.